1. Field of the Invention
The present invention relates to techniques regarding a method of manufacturing electron-emitting devices, a method of manufacturing an electron source, and a method of manufacturing an image-forming apparatus using an electron source.
2. Related Background Art
Of electron-emitting devices, a surface conduction electron-emitting device utilizes the phenomenon that electrons emit when current flows through a thin film having a small area formed on a substrate in parallel to the film plane. Japanese Patent Application Laid-Open No. 7-235255 discloses a surface conduction electron-emitting device using a metal thin film of Pd or the like. This device structure is shown in FIGS. 1A and 1B. In FIGS. 1A and 1B, reference numeral 1 represents a substrate. Reference numeral 4 represents an electroconductive film which is a metal oxide thin film of Pd or the like. This film is subjected to an energization process called an energization forming operation to be later described to locally destruct, deform or decompose the electroconductive film 4 and form a gap 5 having high electric resistance.
In order to improve the electron emission characteristics, an operation called xe2x80x9cactivationxe2x80x9d to be described later is executed in some cases to form an electron-emitting region and films (carbon film) made of carbon and carbon compound near the electron-emitting region This process may be performed by a method of depositing carbon and carbon compound near the electron-emitting region by applying a pulse voltage to the device in an atmosphere which contains organic substance (EP-A-660357, Japanese Patent Application Laid-Open Nos. 07-192614, 07-235255, 08-007749).
Since the surface conduction electron-emitting device has a simple structure and is easy to manufacture, it has an advantage that a number of devices can be arranged in a large area. Various applications utilizing such characteristics have been studied. For example, applications to a charged beam source, a display apparatus and the like are known. One example of an electron source having a number of surface conduction electron-emitting devices is an electron source in which a number of rows are disposed and both ends of each of surface conduction electron-emitting devices disposed in parallel are connected by wirings (also called common wires) (e.g., publications of Japanese Patent Application Laid-Open Nos. 64-031332, 1-283749, 2-57552 and the like).
One example of applications is an image-forming apparatus such as a display apparatus in which an electron source having a number of surface conduction electron-emitting devices is combined with a phosphor which emits visual light when an electron beam is applied from the electron source (e.g., U.S. Pat. No. 5,066,883).
In order to retain uniformity of display images of such image-forming apparatus, various improvements on the forming and activation processes have been proposed. One approach is to judge the completion timing of the activation process from the electrical characteristics during this process (e.g., Japanese Patent Application Laid-Open No. 9-6399).
In addition to surface conduction electron-emitting devices, field emission electron-emitting devices (FE: Field Emitter) are known as another type of an electron-emitting device. One example of FE is a Spindt type. The Spindt type FE is a fine cold cathode constituted of a small conical emitter with a control electrode (gate electrode) formed very near the emitter and having a function of attracting electrons from the emitter and controlling a current quantity. A cold cathode having Spindt type FEs disposed in an array has been proposed by C. A. Spindt, et. al. (C. A. Spindt, xe2x80x9cA Thin-Film Field-Emission Cathodexe2x80x9d, Journal of Applied Physics, Vol. 39, No. 7, p. 3504, 1968).
Techniques for improving an electron emission efficiency of FE has been recently disclosed (Japanese Patent Application Laid-Open No. 10-50206) in which a voltage is applied across the gate electrode and the cathode electrode connected to the emitter in an atmosphere containing organic substance to deposit carbon compound on the emitter surface
One example of an electron source substrate with a number of electron-emitting devices is a simple matrix electron source substrate with electron-emitting devices disposed in a matrix shape of N rows and M columns. When an activation process is performed to deposit carbon or carbon compound on such a substrate, a voltage is applied to the common wires of N rows and M columns connected to device electrodes.
For example, the following methods are performed for the activation process.
(1) A voltage is sequentially applied one line after another from the first row to N-th row.
(2) N rows are divided into several blocks, and a pulse is sequentially applied to each block by shifting the phase. This process is a scroll activation process.
In both the cases (1) and (2), as the number of devices becomes large, it takes a long time to execute the activation process. If the number of blocks of N rows is made small in the case (2), a duty factor of the voltage applied to each row becomes small. Therefore, an activation speed may lower or the electron emission quantity or efficiency may lower so that good electron-emitting devices cannot be manufactured.
One proposed approach to shortening the activation time is to increase the number of lines to which a voltage is applied at the same time. However, this approach is associated with some problems. Namely, the activation process deposits carbon or carbon compound on the electron-emitting region and its nearby area, by decomposing organic substance attached to the device substrate from the atmosphere. Therefore, as the number of devices for which the activation process is executed at the same time, increases, the amount of organic substance decomposed and consumed per unit time on the electron source substrate increases. This results in a variation of the concentration of organic substance in the atmosphere, a lowered carbon film forming speed, and a variation in carbon films depending upon the position in the electron source substrate. Uniformity of manufactured electron sources is therefore degraded.
It is an object of the invention to provide a method of manufacturing electron-emitting devices and an electron source, capable of performing an activation process in a short time.
It is another object of the present invention to provide a method of manufacturing electron-emitting devices and an electron source, capable of forming a carbon or carbon compound film of good crystallinity by a short time activation process.
It is another object of the present invention to provide a method of manufacturing an electron source having a plurality of electron-emitting elements, capable of executing the activation process in a short time.
It is another object of the present invention to provide a method of manufacturing an electron source having a plurality of electron-emitting devices of good uniformity, capable of executing the activation process in a short time.
It is another object of the present invention to provide a method of manufacturing an image-forming apparatus with uniform luminance characteristics.
The present invention provides a method of manufacturing an electron-emitting device comprising a step of forming a pair of conductors on a substrate, the conductors being spaced from each other, and an activation process of depositing carbon or carbon compound on at least one side of the pair of conductors in an atmosphere of carbon compound gas, wherein the activation process includes a plurality of processes of two or more stages including a first process and a second process, and the first process is executed in an atmosphere of the carbon compound gas having a partial pressure higher than a partial process of the second process used as a last activation process.
The present invention also provides a method of manufacturing an electron-emitting device comprising a step of forming an electroconductive film including an electron-emitting region and disposed between electrodes, and an activation process of depositing carbon or carbon compound on the electroconductive film in an atmosphere of carbon compound gas, wherein the activation process includes a plurality of processes of two or more stages including a first process and a second process, and the first process is executed in an atmosphere of the carbon compound gas having a partial pressure higher than a partial process of the second process used as a last activation process.
The present invention also provides a method of manufacturing an electron source comprising a step of forming plural pairs of conductors on a substrate, the conductors being spaced from each other, and an activation process of depositing carbon or carbon compound on at least one side of each of the plural pairs of conductors in an atmosphere of carbon compound gas, wherein the activation process includes a plurality of processes of two or more stages including a first process and a second process, and the first process is executed in an atmosphere of the carbon compound gas having a partial pressure higher than a partial process of the second process used as a last activation process.
The present invention also provides a method of manufacturing an electron source comprising a step of forming a plurality of electroconductive films each including an electron-emitting region and disposed between electrodes, and an activation process of depositing carbon or carbon compound on each of the plurality of electroconductive films in an atmosphere of carbon compound gas, wherein the activation process includes a plurality of processes of two or more stages including a first process and a second process, and the first process is executed in an atmosphere of the carbon compound gas having a partial pressure higher than a partial process of the second process used as a last activation process.
The present invention also provides a method of manufacturing an image-forming apparatus comprising a step of disposing a frame member facing the electron source manufactured according to any one of the electron source manufacture methods described above, the frame member including an image-forming member for forming an image by an electron beam emitted from the electron source.